Glyphosate is the world’s most widely used herbicide with approximately 8.6 billion kg used worldwide between 1974 and 2014. This works out to approximately 0.53 kg being used on every cropping hectare each year. Glyphosate resistant crops account for 56% of all glyphosate used (Benbrook 2016). Glyphosate could be said to be the lynch pin of our current farming system.

It is therefore of some concern that recently the Californian Superior Court awarded $AU390 million to a school groundskeeper dying of cancer allegedly through the use of glyphosate. Add to this the fact that Monsanto faces more than 5,000 similar lawsuits across the United States over a range of glyphosate-related claims.

Further south, a Brazilian court recommended the Brazilian health regulation agency (ANVISA) conduct a toxicological review of glyphosate. The court suspended the registration of glyphosate in Brazil until the herbicide has been reviewed. Brazil will be the world’s largest soybean producer in 2018-19 and over 85% of its soybeans are Roundup Ready.

These court cases have also stoked consumer concern about food safety. While the use of glyphosate is not currently under threat in Australia, the Californian and Brazilian court cases mean Australia’s herbicide stewardship must remain world’s best practice.

What’s on offer in the local supermarket.

The outcomes of these two court cases are based on the 2015 International Agency for research on Cancer (IARC) assessment of glyphosate which said that glyphosate is a potential human carcinogen. The IARC looked at the hazard of glyphosate as a cancer-causing agent however it did not consider how the risks are managed when glyphosate is used according to label directions.

The IARC report also found these are also potential human carcinogens:

· indoor emissions from burning wood

· high temperature frying

· some types of shiftwork

· consumption of red meat

Other agents rated as carcinogenic to humans by IARC include:

· alcoholic beverages

· eating processed meat e.g. salami, ham

· sunlight

· post menopausal hormone therapy

· outdoor air pollution

· the occupation of house painter

· soot, wood dust

The APVMA supports the use of glyphosate in Australia and it can be used safely according to label directions. Following the 2015 IARC report the APVMA conducted its own glyphosate risk assessment and found there was no reason to place it under formal reconsideration.

A number of other regulators around the world have also conducted assessments of glyphosate. These include:

In the largest study of its kind; the US National Cancer Institute conducted the Agricultural health study in Iowa and North Carolina which studied 89,000 farmers and spouses dating back to 1993. Glyphosate was used on 83% of the participant’s farms. The study found no association with solid tumours or lymphoid malignancies including non-Hodgkin’s lymphoma (the cancer of the Californian groundsman awarded damages recently).

What has added to the general public’s concern about glyphosate is California’s Safe drinking water and toxic enforcement act 1986 (Proposition 65) which publishes a list of chemicals known to cause cancer and based on the 2015 IARC report included glyphosate.

Consumer trust

Consumer trust is being tested with multiple stories in the media about these court cases. Many stories are confrontational , often with very little accurate science presented. In fact the general public’s trust in science is seriously under attack by a range of pseudo-scientists out to sell books on their latest theories and ways to stay healthy. The majority of urban residents have little knowledge of where their food comes from or how it is produced. Most consumers have not been trained to analyse information and actually question where stories and information come from.

If that doesn’t get your attention nothing will. The article is well written with a bit of science and quite a bit of emotive language. EWG had sent a range of oat-based breakfast products to a laboratory to be tested for glyphosate residues. Out of the 45 samples from ‘conventional’ agriculture; glyphosate was detected in 43, with 31 samples being above EWGs 0.16 mg/kg stated health benchmark, which by they way no-one else has.

Note that in Australia glyphosate is not registered in oats for pre-harvest application, but is in North America. A problem with these stories is that you have to do a lot of digging to get down to the facts. I will cover this in another blog later.

Australia must maintain good stewardship

While Australia would have the best pesticide regulatory system in the world this is no time for complacency. We must use world’s best stewardship practice with all pesticides. It is essential that advisers and growers follow labels and permits closely as many all our trading partners are often looking for non-tariff barriers to trade. For example China has no maximum residue limit level set for many grains they import so can immediately set an allowable MRL if they want to reduce imports or negotiate on price.

Most grain buyers are also bringing in stricter monitoring of grain quality and can trace back to individual loads. New technology also allows the testing of samples at the grain receivals point. The importance of this issue is reflected in CBH in Western Australia introducing a 3-strikes policy regarding the delivery of contaminated grain as a warning that they are serious about grain quality.

Pre harvest spraying can help reduce weed seed set and enable even ripening of the crop. However application of pesticides close to harvest increases the risk of unacceptable levels of residues being detected in grain.

A management problem with applying pesticides at this time is the grower determining whether the crop is at the right stage. For example when glyphosate is applied to barley the maximum moisture content is 27% (late dough), with a minimum 5 day harvest withholding. Determining 27% moisture takes a bit of effort and the crop can be greener than you would think as shown in the image below. Subsequently applications are then often delayed due to a miscalculation of the acceptable stage or spraying logistics which in turn increases the risk of unacceptable grain residues. On the other hand applying glyphosate too early can affect grain quality and yield.

Top row of barley at 27% -the correct time for glyphosate while the bottom row are 34%, which is too early. Image: Craig Brown

Therefore it is my personal opinion that the late use of glyphosate in crops should be reviewed and alternative weed management strategies be investigated and promoted.

To successfully manage weeds, pests or diseases they must be correctly identified. Mis-identification leads to incorrect control practices which is costly and often makes the problem worse.

Fallopia convolvulus flowers and fruit.

Many people still rely on common names of weeds for their identification, however this leads to problems because many species have multiple common names. Some names are only used within some states or even districts such as Fallopia convolvulus which is known as climbing buckwheat in Queensland and black bindweed in New South Wales.

A more interesting example is Conyza sumatrensis which is normally called tall fleabane. However on the north coast of New South Wales it is often known as cobbler’s pegs. Cobbler’s pegs are actually Bidens pilosa which look totally different.

Originally the naming of plants and animals was based on where they came from. For example any animal from the sea was called a fish. This included whales and dolphins. Many Australian plants were given English names because the colonisers had a European world view. For example the tallest flowering tree in the world - Eucalyptus regnans – was called mountain ash. It looks nothing like European ashes (Fraxinus spp.).

Our modern naming system of genus and species comes from Carl Linnaeus (1707-1778) who divided flowering plants into groups depending on their flowers and fruits.

Unfortunately identifying plants by flowers and fruits is too late for most management strategies. Therefore it is good to use vegetative characteristics to identify plants. This has the major benefits of early weed identification which are cost effective allowing timely management strategies to be implemented.

Starting point for identification

Land plants are divided into groups of increasing complexity in structure, particularly the vascular tissue and how they reproduce and spread. It is generally accepted that land plants commence with green algae and goes through to the flowering plants.

Green algae - contain chlorophyll, no roots or vascular tissue

Mosses & liverworts - have absorbing organs, not roots

Club mosses - single veins in small leaves, and union of stem and leaf without a break in the vascular tissue of the stem. Reproduce by spores.

Horsetails - hollow, jointed stems, reproduce by spores and have an extensive root system

Ferns - highly dissected leaves which unroll from the tip, reproduce by spores and often have rhizomes

Gymnosperms - seeds borne upon scales in a cone or as a naked seed - cycads, ginkgo, conifers

The starting point to narrow down and identify the majority of weeds (flowering plants) is to figure out whether they are monocotyledons or dicotyledons. It is also handy to know over half of weeds come from 5 families of flowering plants - Asteraceae, Brassicaceae, Fabaceae, Poaceae (monocot) and Iridaceae (monocot).

Monocotyledons can be identified by the following characteristics:

plants are herbaceous (no woody parts)

single seed leaves

leaves lack a leaf stalk, with each leaf consisting of an upper strap-like blade and a sheathing base that encloses the stem

ligule on the upper leaf surface is membranous or hairy

leaf veins are parallel with no single main vein

roots are fibrous

includes the major families Poaceae, Liliaceae, Cyperaceae, Orchidaceae, Iridaceae, Amaryllidaceae and Alliaceae

Dicotyledons:

two seed leaves (cotyledons)

shoot system consisting of:

main axis (stem)

leaves attach to the stem at nodes

each leaf consists of lamina, leaf stalk (petiole) and strongly developed main vein with lateral veins (reticulate)

buds in leaf axils and / or at the end of stem

Root system - primary or tap root, with lateral roots

Plant – environment associations

Knowing the types of environment in which certain weeds like to grow can help narrow down the possible candidates. Weeds like annual ryegrass however will grow over a range of environments. Some examples are given below.

Clays

Collecting plants for identification

It is always a good idea to collect specimens for correct identification. There are plant identification services at the various State herbaria. If it is a new species for an area there will often be no charge however if it is a common weed or plant there will be a fee.

With smart phones being ubiquitous technology everyone has the tools to take great photos, but it is annoying to receive blurry images someone expects you to give a miraculous ID from.

Firstly make sure that your images are in focus! Take a series of images. Include the whole plant then get close enough to show detail. Don’t have the subject mixed in with lots of other plants. Isolate the plant you want to photograph from the background or other plants.

You also want light on the front of the subject and not have bright light or reflection behind the subject. Include an object to give an idea of size – fingers, coin etc..

Finally you actually want a flower/seed head and a leaf and stem in the image. These must be in the same plane (side-by-side) otherwise something will be out of focus.

An effective technique is to hold the leaf/stem and flower/seed head up to the sky at arms length with the sun behind you. The image will be in focus, well lit and have necessary detail to allow identification.

Winter grass (Poa annua) is challenging the herbicide resistance crown held by annual ryegrass, with glyphosate-resistant populations being confirmed in Victoria.

Winter grass (Poa annua) - a prolific seeder

Testing has confirmed at least 20 populations of winter grass exhibiting resistance to simazine (group C), propyzamide (group D), group B and group Z herbicides. Another population is resistant to the five herbicide modes of action B, C, D, M and Z.

Winter grass has previously been considered an insignificant weed however the current levels and extent of resistance are surprising. All the resistant populations have developed on golf courses.

A nice, smooth bentgrass golf green

This shows any weed can become a huge problem with changes to management or environment and grain growers should remember that present day problem weeds fleabane and sowthistle were not on the radar 20 years ago.

Winter grass from USA golf courses and sports turf has become resistant to groups B, C, D and M herbicides, while in Britain there is at least one population resistant to paraquat (L) from a vineyard.

Winter grass is a genetically diverse winter annual species that also has perennial populations. A native of Europe, it has now spread around the world, predominantly in temperate countries, but is also found infesting the sub Antarctic Islands of Macquarie and Heard.

It is predominantly a primary colonising weed of disturbed areas and is highly adaptable to heavy grazing and close mowing.

Many golf courses have now lost most of their post-emergent herbicides for controlling winter grass and now rely on pre-emergent herbicides.

Resistance is causing some turf managers to consider using winter grass as a turf species creating a Jekyll and Hyde relationship with the managers of golf courses. While some managers try to control winter grass, others have decided they will live with it and make the most of its useful characteristics. A number of golf courses in Australia and New Zealand have replaced Bent grass greens with winter grass.

In the United States, several universities have golf green winter grass breeding programs for trying to select more perennial lines that have reasonable seed production.

Golf greens are intensively managed and this places enormous selection pressure on the plant species present. Winter grass can set seed under intense mowing regimes and the intensive use of a range of herbicide modes of action has led to this selection of resistant populations.

While more perennial lines tend to develop in cooler climates, there are populations in Adelaide that are becoming perennial and heat-tolerant. A problem with more perennial lines is they produce fewer seeds than annual lines.

It is that time of year again when a farmer’s thoughts turn to burning. Like most things there is more than one way to skin a cat. However I am going to talk about some of the dos and don’ts for narrow windrow burning.

Although at this point you cannot do anything about chaff windrows that have already been produced what you will see is that windrows from a well set up header will have withstood considerable amounts of rain over summer and still be ready to burn. The windrow you can see below has had over 100 mm of rain between harvest and burning.

Windrows that aren't over-threshed remain open and aerated like this one.

Chaff still on top of windrow despite 100 mm rain.Things to note are that the windrow appears prickly and this shows that during harvest the straw was not over threshed. This has allowed the chaff portion to remain high in the windrow which also aids drying after rain. The crop was harvested at a height of approximately 10 cm.

Another critical factor in burning windrows is the meteorological conditions when you start burning.

Starting the burn when the FDI is about 7 which in this case was about 18:00.The use of a fire danger index (FDI) has made stubble burning more of a science than a mystical art. The FDI is determined by temperature, humidity, wind speed and dryness of the fuel. These need to be measured and put into the fire index app to calculate FDI. This means that you need a weather meter, either hand-held or cab mounted, and your mobile phone with the app installed. A very useful app for both Android and Apple is Fire Tools by Mountain Pine Studios.

Doug Smith measuring wind speed, temperature and humidity to feed into the fire app. Also use the Bureau of Meteorology’s MetEye® site for monitoring local predicted changes to wind speed and direction so you can decide whether to press on or call it a night.

This is the sort of result you aim for.As a rule of thumb for the fire index:

Greater than 15 is too high

8 to 10 is ideal

Less than five is often too cool or damp

Starting when the fire index is too high means that the file will rarely stay in the windrow and the fire will burn significant portions of the paddock. See image below.

Too low and the windrows won’t burn as hot as needed to kill weed seeds in the row.

This paddock on another property was cut a little high and the burn started when the Fire index as too high. The fire didn't remain within the rows.Important pointers from Doug & Kerry Smith, Pingrup, WA

Always over-estimate the problem and under-estimate your ability when it comes to fire control

Your aim is to burn the rows not the farm

Buy a good fire lighter as it makes a big difference to the amount you can light per night

Conditions change by the hour so keep measuring conditions as well as knowing what is coming for the next couple of days before you light up.

Check for smouldering rows early the next day so they can be dealt with before the day heats up.